In a number of mechanical systems, as, for example, door actuating systems, there is a need for some sort of a drive to provide a motion input to part of the system to cause some sort of predetermined movement which must be precisely followed by some differing form of movement. For example, in a door actuation system as mentioned previously, a drive unit may be utilized to first move the door from an opened position to a closed position at which time a hook or a latch is operated to latch the door in the closed position.
Subsequently, when the door is to be opened, the drive unit is operated to first release the latch and then move the door from the closed position to the open position.
While these sequential functions can be performed by any of a variety of means including electrical or electronic control circuits, in some instances, it is desirable to accomplish them mechanically with a simple and reliable mechanism which provides for both the transmission of motion from a drive unit to a work piece such as a door latching system and the timing of the motion transmission, that is, the transmission of the motion only at a predetermined time during an operational cycle of the system in which the mechanism is utilized.
The present invention is directed to the provision of such a mechanism.